Dishwasher heating system with dual electrical heating means



June 1, 1965 J. A. FAY 3,186,417

DISHWASHER HEATING SYSTEM WITH DUAL ELECTRICAL HEATING MEANS Filed NOV. 27, 1962 3 Sheets-Sheet l 34 Ffra. 2.

BY'H/S ATTORNEYS HARE/5, MEcH, Ausssu. & KERN June I, 1965 J. A. F AY 3,186,417

DISHWASHER HEATING SYSTEM WITH DUAL ELECTRICAL HEATING MEANS Filed Nov. 27, 1962 3 Sheets-Sheet 2 I I I III I Q I I mT I m I I FIG. 3.

INVEN TOR.

JOHN A. FAY

BY HIS ATTORNEYS HA 122/5, MEG/ Russaz. 8: KERN June 1, 1965 J. A. FAY 3,186,417

DISHWASHER HEATING SYSTEM WITH DUAL ELECTRICAL HEATING MEANS Filed Nov. 27, 1962 3 Sheets-Sheet 3 FIG. 5.

WATER 2.. 66-" HEATER TIMER 60w 4 OFF TIME

INVENTOR. JOHN A. F74) ar HIS A rraeusys HARE/5, K/EcH, RUSSELL 2 Ksmv United States Patent 0 DISHWASHER HEATING SYSTEM WITH DUAL ELEQTRECAL HEATING MEANS Xohn A. Fay, North Hollywood, Caiifi, assignor to Waste King Corporation, Los Angeles, Calif., a corporation of California Filed Nov. 27, 1962, Ser. No. 248,222

.3 Claims. (Cl. 134-57) The present invention relates in general to an automatic dishwasher, i.e., one having its operating cycle controlled by a timer or timer means, and, more particularly, to an improved timer-controlled dishwasher heating system and method.

The basic object of the invention is to provide a dish- Washer heating system which comprises dual heatingmeans, one being a low-output heating means which is on throughout at least a substantial portion of the opcrating cycle of the dishwasher to maintain the desired Water temperature during washing and rinsing and to dry the dishes after they have been washed and rinsed, and the other being a high-output heating means which is energized only when necessary to bring the water temperature up to the desired level prior to washing and rinsing the dishes. Both of the heating means, which may be electrical resistance heating elements, are exposed to the water in the bottom of the dishwasher tub during washing and rinsing, as by being mounted within the tub adjacent the bottom thereof.

With the foregoing construction, While the low-output heating element is energized throughout all or a substantial part of the operating cycle of the dishwasher, the highoutput heating element is energized only when it is submerged in wash or rinse water in the bottom of the dishwasher tub, and then only long enough to bring the temperature of the wash or rinse water up to the desired level for most effective washing, rinsing and preheating for subsequent drying.

The output of the low-output heating element is so selected as to maintain the temperature of everything within the dishwasher tub below a predetermined maximum value, e.g., 200 P, so as to prevent heat damage to items being washed, rinsed and dried, plastic dishwasher parts within the tub, and the like. Since the high-output heating element is on only when submerged, and then only long enough to heat the wash or rinse water in which it is submerged to a predetermined level, which level is sulficiently low to maintain the temperature of the interior of the tub within the desired upper limit, the present invention easily avoids excessive temperatures within the dishwasher tub. Furthermore, the invention accomplishes this without the constant heating-means cycling which is typical of a dishwasher equipped with a single heating means, this being an important feature of the invention.

Another important advantage of the invention is that it accomplishes its basic purpose with a very simple electrical circuit for the heating system. In other words, since the low-output heating element is on throughout all or a major portion of the operating cycle, its circuitry is very simple, it being necessary only to provide means for energizing the high-output heating element when heating of the washand rinse water is necessary, and for de-energizing this heating element when the desired wash and rinse water temperatures have been attained.

Another object of the invention is to provide the dishwasher with a timer or timer means having switch means for energizing the high-output heating element at selected points during the operating cycle. Preferably, one such point corresponds to the introduction of the wash water for the main washing operation, and another corresponds to the introduction of the rinse water for final rinsing of the dishes after washing. If desired the water in any other phase of the cycle can be heated by the high-output heating element also.

Another object of the invention is to provide the dishwasher with temperature responsive switch means, e.g., a thermostat switch, for de-energizing the high-output heating element when the'desired water temperatures for the main washing operation and the final rinsing operation have been achieved.

Another and important object of the invention is to provide a timer having switch means for de-energizing itself upon energization of the high-output heating element until such time as the desired wash and final rinse water temperatures are attained, the thermostat switch re-energizing the timer, which then de-energizes the high-output heating element, when the Water temperature reaches the de sired level. the dishwasher is interrupted, upon the introduction of water for the main washing operation and for the final rinsing operation, until such time as the water temperature attains the preselected level, whereupon the operating cycle is resumed. This insures that the water temperature will be elevated to the desired level before the main washing operation and the final rinsing operation.

Preferably, the low-output and the high-output electrical heating elements are sheathed in a conventional manner for submerged operation. While the two heating ele ments may be separately sheathed, and the provision of such a heating system is one object of the invention, an important object is to enclose both heating elements in side-by-side, spaced relation within a single sheath. This results in a more economical structure, and one which is more compact and takes up less space in the bottom of the dishwasher tub, which are important features.

The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results thereof which will be apparent to those skilled in the art to which the invention relates in the light of this disclosure, may be achieved with the exemplary embodiments of the invention de scribed in detail hereinafter and illustrated in the accompanying drawings, in which:

FIG. 1 is a side elevational view of a front loading dishwasher which embodies the invention;

FIG. 2 is an enlarged, fragmentary view taken as indicatedby the arrowed line 2-2 of FIG. 1 (and also as indicated by the arrowed line 22 of FIG. 3);

FIG. 3 is a sectional view taken as indicated by the arrowed line 33 of FIG. 2;

FIG. 4 is an enlarged sectional view taken along the arrowed line 44 of FIG. 2;

FIG. 5 is a highly simplified, fragmentary, diagrammatic view illustrating the heater circuitry of the invention and the control system therefor;

FIG. 6 is a fragmentary view illustrating a portion of the operating cycle of the dishwasher of the invention;

FIG. 7 is a fragmentary view, similar to a portion of FIG. 2, illustrating another embodiment of the invention; and

FIG. 8 is an enlarged sectional View taken along the arrowed line 88 of FIG. 7.

Referring initially to FIG. 1 of the drawings, the dish washer of the invention is designated generally by the numeral 19 and includes a tub 12 provided with a downwardly-opening front door 14. Dishes to be washed, rinsed and dried within the tube 12 are adapted to be supported therein by baskets 16 and 18. During the main washing and rinsing operations of the operating cycle of the dishwasher 10 (and during the pre-rinsing operation which may be carried out prior to the main washing operation), water is drawn from the bottom of With this construction, the operating cycle of the tub 12 by a motor-pump assembly 28 and is delivered to a water distributing impeller 22 which sprays the water over dishes in thebaskets 1e and 13.

The heating system of the invention is designated generally by the numeral 24- and is located within the tub 12 adjacent the bottom thereof and in communication with the interior of the tub.

The structure of the dishwasher it has been illustrated and described in a superficial way only merely to outline the environmental setting of the invention. It will be understood that the dishwasher lit includes numerous additional components, preferably electrically operated, for performing such functions as introducing water into the tub l2 prior to the main washing and rinsing operations (and prior to the pie-rinsing operation preceding the main washing operation if such a pre-rinsing operation is utilized), for draining the water from the tub 12 after each Washing or rinsing operation, for circulating heated air over dishes in the baskets 16 and 18 during the drying operation, and the like. These various operations are carried out under the control of a timer or timer means which is shown diagrammatically at 26 in FIG. of the drawings and which includes the usual electric timer motor, control switches, motor-driven cams for operating the control switches, and the like. These have been shown in FIG. 5 of the drawings only to the extent necessary for an understanding of the present invention. For a more complete disclosure of components which are not illustrated in the drawings and which are conventionally incorporated in automatic, timer-controlled dishwashers, attention is directed, for example, to Patent No. 2,918,068, issued December 22, 1959 to H. E. Karig.

Turning now to FIGS. 2 and 3 of the drawings in particular, the heating system 24 is shown as mounted on the bottom wall of the tub 12 within a sump 28 from which water is drawn by the motor-pump combination 2%? when it is in operation. With this construction, the heating system 24 is below the static water level 30, FIG. 3, in the tub 12.

The heating system 24 includes a sheath 32 containing electrical insulating material in which are embedded two resistance heating elements 36 and 38 in side-by-side, spaced relation. This provides a very compact heating system 24 which occupies but little space in the bottom of the tub 12, and which may be manufactured economically.

The heating element 36 has a relatively low heat output, while the heating element 33 has a considerably higher heat output. For example, the heating element 36 may be a 400-watt element and the heating element 38 may be a IZOO-watt element.

The low-output heating element 36 is preferably on continuously and without interruption throughout the en tire operating cycle of the dishwasher it), although it may be on throughout less than the total cycle. The highoutput heating element 38 is energized only upon the introduction of water into the tub 12 prior to the main washing and rinsing operations, being on only long enough to bring the water temperature up to a predetremined level. As will be explained, the high-output heating element 38 is adapted to be energized by the timer 26, and is adapted to be de-energized when the proper water temperature is reached by a temperature responsive switch means or thermostat switch 40 exposed to the interior of the tub 12. As shown in FIGS. 2 and 3 of the drawings, the thermostat switch 40 is mounted on the bottom wall of the tub 12 below the heating elements 36 and 38 and is below the static water levele 30 so as to respond accurately to the water temperature.

Turning to FIG. 5 of the drawings, it will be seen that the motor (not specifically shown) of the timer 26 is connected across power input lines 42 and 44 through either the thermostat switch 40, or a switch means 46 comprising a switch element 48 engageable with either of two contacts 50 and 52. It will be noted that the thermostat switch 40 and the switch element and contact combination 48 and 5d connected in parallel so that closure of the thermostat switch 4%, or engagement of the switch element 43 with the contact 5%, will energize the motor of the timer 26.

The switch element 43 is movable between the contacts 5% and 52 by a cam, not shown, driven by the motor of the timer 26 in a conventional manner. The cam which controls the switch element is so designed that it shifts this switch element from engagement with the con tact 5% into engagement with the contact 52 whenever euergization of the high-output heating element 38 is required, this heating element being connectible across the lines 42 and 4 by the switch element and contact combination 28 and 52.

in order to obtain continuous energization of the lowoutput heating element 3-5? without interruption throughout the entire operating cycle of the dishwasher it this heating element is connected directly across the lines and 44. Thus, the lowoutput heating element is energized as long as a main, on-otf switch 54 in the line 42 is closed. As is conventional, the main switch 54- forms part of the timer and is adapted to be closed manually to start the operating cycle of the dishwasher lt being opened by the timer 26 at the end of the operating cycle by a cam, not shown, driven by the motor of the timer.

As previously explained, the showing of FIG. 5 of the drawing has been limited to that necessary to provide an understanding of the present invention. The timer 26, of course, is equipped with other cam-operated switches, not shown, for performing various other wellknown functions associated with automatic dishwasher operation.

Considering the operation of the present invention, it will be assumed that the water to be used for the main washing operation and the final rinsing operation is to be heated to a predetermined level, determined by the thermostat switch it). The operating cycle of the dishwasher l 's is initiated in the usual manner by manipulating the control knob, not shown, of the timer 26 in such a way as to close the main switch 54. This results in energization of the timer motor and of the low-output heating element 35, the timer causing the dishwasher to run through the various phases of its operating cycle.

When the water for the main washing operation is introduced into the tub 12 in a conventional manner, the timer 26 shifts the switch element 48 from a position where it engages the contact 50 to a position where it engages the contact 52. As shown diagrammatically in FIG. 6 of the drawings, this results in de-energization of the timer, as indicated at 6%, and results in energization of the high-output heating element or water heater 38, as indicated at 62. The timer 26 remains de-energized until the water temperature, as sensed by the thermostat switch 40, reaches the desired value. Since the time required to accomplish this is variable, depending upon the initial water temperature, the rate of heat loss from the dishwasher 1t), and the like, the intervals 6i and 62 have been shown as of indeterminate length with respect to time by utilizing dotted lines for the crests thereof.

Once the thermostat switch 49 closes in response to attainment of the desired water temperature, the resulting re-energization of the timer 26 causes resumed rotation of the cam which controls the switch element 43. This cam, after a brief interval, restores the switch element 48 to its initial position, viz., the position wherein it is in engagement with the contact 50, so as to maintain energization of the timer .26 even though a slow decrease in the water temperature causes the thermostat switch to open. At the same time, the high-output heating element 38 is de-energized.

Thus, the high-output heating element 38 is energized only long enough to elevate the water temperature to the level desired for the main washing operation, the operating cycle of the dishwasher it? being interrupted, by deenergization of the timer 26, until this is achieved. As

soon as the desired Water temperature is reached, the normal operating cycle of the dishwasher isresumed'.

Similarly, the timer is de-energized and the heating element 38 is energized upon the introduction of the water required for the final rinsing operation, and prior to commencement of this operation, as indicated at 64 and 66 in FIG. 6 of the drawings. 5

Referring to FIGS. 7 and 8 of the drawings, illustrated therein is a heating system 70 of the invention which is identical to the heating system 24, except that the low output and high-output heating elements 36 and 38 are embedded in insulating material in separate sheaths 72 and 7 4, instead of in the common sheath 32. In all other respects, the heating system 70 is identical to the heating system 24.

Although exemplary embodiments of the invention have been disclosed herein for purposes of illustration, it will be understood that various changes,tmodifications and substitutions may be incorporated in such embodiments without departing from the spirit of the invention as defined by the claims which follow.

I claim:

1. In an electrical heating system for a dishwasher which includes a tub adapted to be filled with water to a predetermined static water level and adapted to contain dishes to be washed, rinsed and dried, and which includes timer means for controlling the operating cycle of said dishwasher, the combination of:

(a) low-output electrical resistance heating means in said tub above the bottom thereof and below said static water level;

(b) high-output electrical resistance heating means in said tub above the bottom thereof and below said static water level;

(c) means, including switch means controlled by said timer means, for energizing and de-energizing said low-output heating means;

(d) means, including switch means controlled by said 6 timer means, for dc-energizing said timer means and for energizing said high-output heating means at a predetermined point in the operating cycle of said dishwasher;

(e) means, including temperature responsive switch means in said tub adjacent the bottom thereof and below said static water level, for re-energizing said timer means and for de-energizing said high-output heating means in response to a predetermined maximum temperature;

(f) said low-output and high-output heating means respectively comprising low-output and high-output electrical resistance heating elements; and

(g) waterproof sheathing means enclosing said heating elements.

2. An electrical heating system as set forth in claim 1 wherein said sheathing means includes a single sheath enclosing said heating elements in spaced relation.

3. An electrical heating system as set forth in claim 1 wherein said sheathing means includes separate'sheaths respectively enclosing said heating elements.

References Cited by the Examiner UNITED STATES PATENTS 1,183,925 5/16 Waters 219-204 2,081,636 5/37 Minors 134-570 2,710,818 6/55 Winters 134-18 2,781,765 2/57 Steidley 134-57 2,991,791 7/61 Rozenfeld 134-58 2,994,329 8/61 Catlin et al. 134-58 3,026,628 3/62 Berger et al. 134-108 X 3,041,212 6/62 Booth 134-107 X 3,049,133 8/62 Jacobs 134-57 3,089,791 5/63 Stirling et al. 134-18 CHARLES A. WILLMUTH, Primary Examiner.

M. O. WOLK, Examiner. 

1. IN AN ELECTRICAL HEATING SYSTEM FOR A DISHWASHER WHICH INCLUDES A TUB ADAPTED TO BE FILLED WITH WATER TO A PREDETERMINED STATIC WATER LEVEL AND ADAPTED TO CONTAIN DISHES TO BE WASHED, RINSED AND DRIED, AND WHICH INCLUDES TIMER MEANS FOR CONTROLLING THE OPERATING CYCLE OF SAID DISHWASHER, THE COMBINATION OF: (A) LOW-OUTPUT ELECTRICAL RESISTANCE HEATING MEANS IN SAID TUB ABOVE THE BOTTOM THEREOF AND BELOW SAID STATIC WATER LEVEL; (B) HIGH-OUTPUT ELECTRICAL RESISTANCE HEATING MEANS IN SAID TUBE ABOVE THE BOTTOM THEREOF AND BELOW SAID STATIC WATER LEVEL; (C) MEANS, INCLUDING SWITCH MEANS CONTROLLED BY SAID TIMER MEANS, FOR ENERGIZING AND DE-ENERGIZING SAID LOW-OUTPUT HEATING MEANS; (D) MEANS, INCLUDING SWITCH MEANS CONTROLLED BY SAID TIMER MEANS, FOR DE-ENERGIZING SAID TIMER MEANS AND FOR ENERGIZING SAID HIGH-OUTPUT HEATING MEANS AT A PREDETERMINED POINT IN THE OPERATING CYCLE OF SAID DISHWASHER; (E) MEANS, INCLUDING TEMPERATURE RESPONSIVE SWITCH MEANS IN SAID TUBE ADJACENT THE BOTTOM THEREOF AND BELOW SAID STATIC WATER LEVEL, FOR RE-ENERGIZING SAID TIMER MEANS AND FOR DE-ENERGIZING SAID HIGH-OUTPUT HEATING MEANS IN RESPONSE TO A PREDETERMINED MAXIMUM TEMPERATURE; (F) SAID LOW-OUTPUT AND HIGH-OUTPUT HEATING MEANS RERESPECTIVELY COMPRISING LOW-OUTPUT AND HIGH-OUTPUT ELECTRICAL RESISTANCE HEATING ELEMENTS; AND (G) WATERPROOF SHEATHING MEANS ENCLOSING SAID HEATING ELEMENTS. 